Ten
years ago Twin Disc was called upon to modify the transmission on Crash/Fire/Rescue
Vehicles. The problem? Their engines would get bogged down dispersing
the fire-fighting agent. The goal? Make a transmission that lets the engine
run at whatever speed necessary to maneuver around the fire and still
have enough power to disperse the firefighting agent. The answer? The
QuickShift transmission, a technology with origins in farming machinery.

This
transmission is a smart, shock-absorbing system. When it is shifted into
forward or reverse, energy is transmitted and controlled by the transmission
and, depending on the power requirements at any instant, is redistributed
through the driveline at low torque in the safest and most efficient manner.
And with the help of some newly designed, hydraulically operated, multidisc
clutch packs and solenoids, the system adapts quite well for use in the
marine environment, according to Dave Johnson, manager of marketing and
communications for Twin Disc. Although the clutch technology has a patent
pending and details about it are being held close to the vest, Jim Kearney,
vice president of marketing and sales for Twin Disc, did tell me a little
about the solenoids.

The
QuickShift transmission uses proportional solenoids that allow for a trolling
mode without the need for a trolling valve. "It simplifies the system,"
says Kearney, adding that a traditional trolling valve setup requires
numerous shims and adjustments. "Once it [the QuickShift] leaves
[the factory] it needs no further adjustment," Kearney adds.

And
wouldn't it be nice to shift your boat's diesels into gear
without lurching and leaving guests grabbing for a handrail? How about
being able to exit your boat's slip without rocketing out like a
spaceship breaking gravity? Or maybe improve close-quarter handling? "Until
now, large diesel-powered boats could not effectively maintain vessel
control below 5 knots. Reducing engine rpm that low would likely stall
the engine," says Klaus Meyersieck, Twin Disc product manager for
marine transmissions. "The QuickShift's unique ability to
regulate engine torque at extremely low speeds allows boat operators to
slow prop speed down to 50 rpm or less. This affords controllable maneuvering
at slower speeds than even conventional trolling-type transmissions."